This invention pertains in general to the field of telephone circuitry. Specifically, the invention relates to logic circuitry and method for generating different output signals applied to a telephone line to which one or more telephone station sets are connected.
There has been an unfilled need for a device by which two or more persons who use a common telephone line can be individually signalled. One such need is where a secretary and an individual who directs or supervises the secretary (hereafter simply referred to as "boss") use the same telephone line on a business PBX or key telephone system. The boss does not wish to answer the telephone, if the caller desires to talk to the secretary. On the other hand, if the call is for the boss, the boss desires to be signalled. Thus, a need exists for a device which can interpret the number and timing of rings, controlled by the calling party, to provide two different identifying signals, one indicating that the boss is being called, the other that the secretary is being called. If the caller, wishing to speak with the secretary, would follow a predetermined sequence of the number and timing of ringing signals, the caller could produce information sufficient to enable suitable apparatus to distinguish such a caller's ringing signals from the ringing signals of all other callers.
Another need exists whereby an ordinary telephone line may be used to signal the control of a remote appliance, e.g. an air conditioner unit in a home, office or factory.